As an example of a conventional technology for managing a water treatment plant, there is a publicly known plant management system in which in a management center connected with a water treatment plant via a communication line, the operating state of the water treatment plant is monitored and the operating state is evaluated, and operating conditions are changed based on the evaluation result (see Patent Document 1, for example). In such a plant management system of a water treatment plant, evaluation of the operating state of the water treatment plant is performed based on the measurement values by the sensors provided to the water treatment plant, for example.
In general, as sensors provided to a water treatment plant, typical industrial instrument is used. Specifically, low-cost sensors such as a conductivity meter for measuring conductivity of the water to be treated, a turbidity meter for measuring turbidity of the water to be treated, an absorptiometer for measuring absorbance of the water to be treated, a pH meter for measuring potential Hydrogen (pH) of the water to be treated, and an oxidation-reduction potentiometer for measuring oxidation-reduction potential (ORP) of the water to be treated, are used generally.